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Vapour pressure

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Description of key information

Vapour pressure:

27.6 hPa at 20°C (OECD 104)

Key value for chemical safety assessment

Vapour pressure:
27.4 hPa
at the temperature of:
20 °C

Additional information

Two reliable measured vapour pressure values are available for M4Q. A vapour pressure of 27.6 hPa at 20°C was obtained for the substance in accordance with OECD TG 104. The result is considered to be reliable and selected as key study. The value selected as key study is for the registration substance as placed on the market, which has a purity of >80% M4Q (1,1,1,5,5,5-hexamethyl-3,3-bis[(trimethylsilyl)oxy]trisiloxane) and 5 - ≤20% M6Q2 (1,1,1,5,5,5-Hexamethyl-3-[(trimethylsilyl)oxy]-3-trisiloxanyl tris(trimethylsilyl) orthosilicate (CAS# 18602-90-9)) as a named impurity.

A second vapour pressure study using a sample of M4Q with stated purity >99% reported a vapour pressure of 15 Pa at 25°C. The study was conducted according to generally accepted scientific principles and is considered to be reliable.